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<html lang="en">

<head>
    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>计算器</title>
    <link rel="stylesheet" href="./index.css">
</head>

<body>
    <table border="1" cellspacing="20" cellpadding="40">
        <thead>
            <tr>
                <td colspan="4" align="center" class="user-input">
                    <input type="text" placeholder="请输入">
                </td>
            </tr>
        </thead>
        <tbody>
            <tr>
                <td class="other">C</td>
                <td class="other">⬅</td>
                <td class="orange">÷</td>
                <td class="orange">×</td>
            </tr>
            <tr>
                <td class="num">7</td>
                <td class="num">8</td>
                <td class="num">9</td>
                <td class="orange">-</td>
            </tr>
            <tr>
                <td class="num">4</td>
                <td class="num">5</td>
                <td class="num">6</td>
                <td class="orange">+</td>
            </tr>

        </tbody>
        <tfoot>
            <tr>
                <td class="num">1</td>
                <td class="num">2</td>
                <td class="num">3</td>
                <td rowspan="2" class="orange">=</td>
            </tr>
            <tr>
                <td class="other">√</td>
                <td class="num">0</td>
                <td class="num">.</td>
            </tr>
        </tfoot>
    </table>
</body>

</html>